The present invention relates in general to an image sensor with active sensor elements, more in particular to a CMOS image sensor.
Image sensors are generally known. Reference may be made, for example, to the publication xe2x80x9cCMOS Image Sensors: Electronic Camera-On-A-Chipxe2x80x9d by Erik R. Fossum in xe2x80x9cProceedings of the IEEE International Electron Devices Meeting 1995, pp. 17-25xe2x80x9d.
In general, an image pick-up or image sensor comprises a plurality of sensor elements which are positioned next to one another in a regular array. Each sensor element is sensitive to light and provides an electric signal which corresponds to the light received by the sensor element. When an image is projected onto the array of sensor elements of the image sensor, each sensor element provides an electric signal which is representative of one picture element or pixel of the projected picture.
Each of the active sensor elements comprises a photosensitive member such as, for example, a photodiode for converting a light signal into an electric signal, and an amplifier member for amplifying the electric signal generated by the photosensitive member. The sensor element is to be provided with a supply voltage and control signals for causing the sensor element to function. Furthermore, the output signals of the sensor elements are to be offered to a signal-processing device. For this purpose, conductive tracks extend over the surface of the pixel matrix, which tracks are connected to respective inputs or outputs of the sensor elements. Said tracks are made of metal and accordingly are impermeable to light, so that these tracks lead to a reduction in the surface area of the sensor elements which is effectively available for receiving light.
It is a main object of the present invention to provide an active image sensor in which the number of connection tracks extending over the sensor matrix is reduced while the functionality remains the same. A major advantage offered thereby is an improvement in the effective light-receiving surface area of each sensor element.